Components of Income Tax Expense (Benefit) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2010
Current
Federal	$ 47,543	$ 47,698	$ 30,080
State and local	2,756	1,246	1,333
Foreign	830	2,070	1,347
Current Income Tax Expense (Benefit), Total	51,129	51,014	32,760
Deferred
Federal	67	3,950	(6,804)
State and local	(69)	3,599	1,399
Foreign	777	(67)	(705)
Provision for deferred income taxes	775	7,482	(6,110)
Income tax expense	$ 51,904	$ 58,496	$ 26,650